When it comes to feeding your baby, it's hard to beat breast milk. A mother's milk provides a baby all the nutrients needed and is linked to various beneficial health outcomes later in life.
However, a recent study found that one of those improved outcomes is not necessarily a lower risk of obesity.
When researchers compared a large group of women who breastfed their children considerably longer than another large group of women, they found little difference between the children's weights 11 years later.
The body mass index and various other measures of obesity were approximately the same in the children of both groups of mothers.
The study, led by Richard M. Martin, PhD, of the School of Social and Community Medicine at the University of Bristol in England, aimed to find out whether the length of time a child is breastfed has any apparent effect on the child's obesity risk.
The researchers included 17,046 mothers and their children in the study. All the women were being seen at one of 31 different maternity hospitals and clinics in Belarus.
The clinics were randomly assigned to provide the women either with usual care (15 clinics) or to provide an intervention that heavily promoted breastfeeding for the mothers.
The researchers were able to follow up with 81 percent of the women over a decade later, when their children were an average age of 11.5 years old.
During the course of the study, women receiving treatment at the clinics with an especially heavy emphasis on breastfeeding were found to breastfeed their babies for longer than the women at the usual care clinics.
Six percent of the women at the usual care clinics exclusively breastfed their babies until the children were 3 months old, compared to 43 percent of the women at the clinics promoting breastfeeding.
When the children were six months old, 8 percent of the women going to the clinics with the breastfeeding intervention and 0.6 percent of the women at the usual care clinics were still exclusively breastfeeding their babies.
When the researchers followed up with the women's children nearly 12 years later, the researchers assessed the children's body mass index (BMI), fat percentage, waist circumference and skinfold thickness at the triceps. The BMI is a ratio of height to weight that is used to classify individuals' weight.
The researchers found the differences between the groups in BMI, fat percentage, skinfold thickness and waist circumference were very small. Calculations revealed that the differences were so small that they could have been due to chance.
The researchers concluded the intervention did help improve how long the women chose to breastfeed their babies exclusively. However, the strong promotion of breastfeeding did not appear to affect whether the children were overweight a decade later.
"Breastfeeding has many advantages but population strategies to increase the duration and exclusivity of breastfeeding are unlikely to curb the obesity epidemic," the researchers wrote.
The study was published March 12 in the journal JAMA. The research was funded by grants from the European Union, the Canadian Institutes of Health Research and the US National Institutes of Health.
Two authors have given a talk at the Nestle Nutrition Institute, and another has received meeting expenses from Nestle Nutrition Institute that were unrelated to this study.